ML20212L235
| ML20212L235 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 01/21/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20212L233 | List: |
| References | |
| NUDOCS 8701290381 | |
| Download: ML20212L235 (8) | |
Text
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UMTED STATES NUCLEAR REGULATORY COMMISSION g .I WASHINGTON. D. C. 20555
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ATTACHMENT 1 SUPPLEMENTAL SAFETY EVALUATION REPORT BY THE OFFICE OF NUCLEAR REACTOR REGULATION
, GULF STATES UTILITIES COMPANY RIVER BEND STATION DOCKET NUMBER 50-458 5.2.4 Reactor Coolant Pressure Boundary Inservice and Testing
- 5.2.4.3 Evaluation of Compliance with 10 CFR 50.55a(g) for River Bend Station This evaluation supplements conclusions in this section of NUREG-0989, which i
addressed the definition of examination requirements and the evaluation of L compliance with 10 CFR 50.55a(g). Paragraph IWA-1500 of Section XI of the 1
ASME Boiler and Pressure Vessel Code (ASME Code) requires that the design of the Code Class 1 and 2 components of the reactor coolant pressure boundary i incorporate provisions for access for inservice examinations. Paragraph 50.55a(g),10 CFR Part 50, defines the detailed requirements for the pre-service and inservice inspection programs for light-water-cooled nuclear power facility components. Based upon the construction permit date of March 25, 1977,
- this section of the regulations requires that a preservice inspection program be developed and implemented using at least the edition and addenda of Section XI of the ASME Code applied to the construction of the particular components.
The components (including supports) may meet requirements set forth in sub-sequent editions and addenda of this Code which are incorporated by reference in 10 CFR 50.55a(b) subject to the limitations and modifications listed therein.
, The applicant has prepared the PSI Program based on compliance with the
, requirements of the 1977 Edition of the Code including Addenda through
[ Summer 1978 except for the reactor pressure vessel (RPV) which was examined t
in accordance with ASME Section XI 1974 Editions through summer 1975 Addenda or where specific written relief is requested.
In an attachment to a letter dated May 12, 1986 (J. E. Booker to H. R. Denton),
the applicant revised the ISI program plan (Rev. 4) updating the plan and submitting an additional relief request (R-0012). The staff evaluation consisted of reviewing these submittals and determining if relief from the
. Code requirements is justified pursuant to 10 CFR 50, paragraph 50.55a(a)(3).
1 Relief from the Code requirements has been allowed for those requirements that,
. if implemented, would result in hardships or unusual difficulties without a
- compensating-increase in the level of quality and safety. On the basis of
, granting-relief from these preservice examination requirements, the staff concludes that the Preservice Inspection program is in compliance with 10 CFR 50.55a(g)(3).
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ATTACHMENT 2 APPENDIX L SUPPLEMENTAL ~ SAFETY EVALUATION REPORT PRESERVICE INSPECTION RELIEF REQUEST GULF STATES UTILITIES COMPANY RIVER BEND STATION DOCKET NO.: 50-458 I. INTRODUCTION For nuclear power facilities whose construction permit was issued on or after July 1,1974,10 CFR 50.55a(g)(3) specifies that components shall meet the preservice examination requirements set forth in editions and addenda of Section XI of the ASME Boiler and Pressure Vessel Code applied to the construction of the particular component. The provisions of 10 CFR 50.55a(g)(3) also state that components (including supports) may meet the requirements set forth in subsequent editions and addenda of this Code which are incorporated by reference in 10 CFR 50.55a(b) subject to the limitations and modifications I
listed therein.
In the River Bend Station ISI Program, Revision 4, submitted on May 12, 1986, l the applicant requested relief (R-0012) from ASME Section XI Code requirements l which the applicant has determined to be not practical and provided a t technical justification. At our request the applicant by letter dated i November 19, 1986, provided additional information. Therefore, the staff evaluation consisted of comparing the applicant's submittals to the I requirements of the applicable code edition and addenda and determining if i relief from the Code requirements was justified.
II. TECHNICAL REVIEW CONSIDERATIONS The applicants submittal dated May 12, 1986 does not change the staff's discussion of the " Technical Review considerations in Appendix L of SSER No. 3.
For the basis of the staff review of the River Bend unit 1 Preservice Inspection (PSI) Program and requests for Relief from impractical requirements see Appendix L SSER No. 3.
III. EVALUATION OF RELIEF REQUESTS In Revision 4 of the River Bend Station PSI Program submitted May 12, 1986 the applicant requested relief from certain specific preservice inspection requirements. At our request the applicant provided additional information in a letter dated November 19, 1986. Based upon the information submitted by the applicant and the staff's review of the design geometry, and materials of construction of the components, certain preservice requirements of the ASME Boiler and Pressure vessel code,Section XI have been determined to be L __________ _ _ _ _ . _ _ _ _ _ _ _ . - - - - - - -
2 impractical to perform. The applicant has demonstrated that either (1) the proposed alternates would provide an acceptable level of quality and safety or (2) compliance with the specified requirements of this section would in hardships or unusual difficulties without a compensating increase in the level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(a)(3), conclusions that these preservice requirements are impractical are justified as follows.
Unless otherwise stated, references to the Code refer to the ASME Code,Section XI,1977 Edition, including Addenda through Summer 1978.
4 A. Relief Request R0012A, Reactor Vessel Shell - Longitudinal Welds, Category B-A, Item Bl.1 Weld BG Code Requirements Longitudinal shell welds are required to be volumetric inspected for preservice inspections in accordance with ASME Code Section XI 1974 Edition through and including 1975 Addenda.
Relief Request:
Relief is requested from performing 100% of the Code required volumetric examination of the longitudinal shell weld BG on the reactor vessel.
Applicant's Basis for Request:
Preservice ultrasonic inspection coverage of longitudinal shell weld BG was reduced at an adjacent nozzle due to interference with the automated ultrasonic inspection equipment.
Welds have been volumetrically examined by radiography and hydrostatically tested, found acceptable in accordance with ASME Section III Class 1 requirements.
Complete preservice ultrasonic inspection coverage was achieved for transverse reflectors for longitudinal shell weld BG. Coverage for parallel reflectors included 100% of the weld and was approximately 95% for adjacent metal in the
\ t zone due to interference with the automatic inspection equipment caused by adjacent nozzle.
- Staff Evaluation and
Conclusions:
The staff has reviewed the applicants request for relief, including the attached sketches showing the examination limitations for this weld. As i a result of this review, the staff has concluded that a significant i
percentage of the code-required examination has been performed and that the reactor vessel and/or the nozzle would have to be redesigned and refabricated in order to complete the remainder. The staff concludes that a significant portion of the Section XI volumetric examinations and Section III fabrication examinations provide an acceptable level of preservice structural integrity and that compliance with the specific requirement of 100% examination per Section XI would result in hardship and unusual difficulties without a compensating increase in the ' level of quality and safety. Therefore, relief is granted. _ _ _ . _ _ . _ _ _ _ ___ __._
Relief Request R00128, Reactor Vessel to Nozzle Welds, Category B-D, Item Bl.4.
Code Requirements:
Nozzle-to-vessel welds are required to be volumetric (ultrasonic) inspected for preservice inspection in accordance with ASME Section XI 1974 Edition through and including Summer 1975 Addenda.
Relief Request:
Relief is requested from 100% inspection from the nozzle side of the following nozzle-to-vessel welds; N1A N2A N3A N6A NIB N2B N3B N6B 1 N2C N3C N6C !
N2D N30 N7 N2E N4A N8 N2F N48 N9A N2G N4C N98 N2H N40 N10 N2J NSA N16 N2K NSB Applicant's Basis for Request Nozzle-to-vesse' welds were fabricated in accordance with ASME Section III Class 1 requirements. Preservice inspections were performed in accordance with ASME Section XI 1974 Edition through Summer 1975 Addenda.
1 Due to the geometry of the nozzles, the ultrasonic examination from the outside surface is only possible from the vessel side of the nozzle-to-vessel welds.
I l Welds have been volumetrically examined by radiography and hydrostatically
! tested, found acceptable in accordance with ASME Section III Class 1 i
requirements.
l The preservice ultrasonic inspection of the nozzle-to-vessel welds listed above achieved full coverage for parallel and transverse reflectors from the vessel side of the welds. Approximately 50% of the required volume on thenozzle side of the weld was inspected for parallel reflectors from the vessel side of the welds. All of the weld metal was examined. Areas of the vessel-to-nozzle weld were not covered for parallel reflectors, and some areas v -re not covered for transverse reflectors.
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Staff Evaluation and
Conclusion:
The staff has reviewed the applicants request for relief, including the attached sketches showing the examination limitations for the individual nozzles. As a result of this review, the staff has concluded that a significant percentage of the code required examination has been performed and that the reactor vessel and/or nozzles would have to be redesigned in order to complete the remainder. Later Editions of the ASME Section XI Code minimized -
the difficulties of performing a full thickness examination by reducing the required examination volume.
The staff concludes that the limited Section XI volumetric examinations and the Section III fabrication examinations provide an acceptable level of preservice structural integrity and that compliance with the specific requirements of Section XI would result in hardship or unusual difficulties without a compensating increase in the level of quality and safety.
Therefore, relief is granted.
Relief request R0012C, Vessel Supports, Category B-H, Item Bl.12-Code Requirements:
Vessel support welds are required to be volumetric (ultrasonic) examined for preservice inspection in accordance with ASME Section XI,1974 Edition through Summer 1975 Addenda, IWB-1500-1, examination category B-H, Item Bl.12.
Relief Request:
Relief is requested from the ultrasonic examination of 100% of the vessel supports.
Applicant's Basis for Request:
Weld was fabricated in accordance with ASME Section III Class 1 requirements.
Preservice inspections were performed in accordance with ASME Section XI 1974 Edition through and including Summer 1975 Addenda.
Due to the configuration, there is sufficient area to perfom a meaningful ultrasonic examination from the OD surface, one side only (support skirt side).
Weld has been volumetrically examineu by radiography and hydrostatically tested, found acceptable in accordance with ASME Section III Class 1 requirements.
Weld was examined volumetrically (manual ultrasonic) from the 00 surface, support skirt side of the weld.
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4 5-Staff Evaluation and
Conclusion:
i The staff has reviewed the applicant's request for relief, including the sketches showing the examination limitations. As a result of this review, the staff has concluded that a significant percentage of the code-required examination has been performed. Later editions of the ASME Section XI Code allow volumetric examinations from one side. The staff concludes that the
^ limited Section XI volumetric examinations and the Section III fabrication i examination provide an acceptable level of preservice structural integrity and
' establish an adequate baseline examination record for future inservice inspection. Compliance with the specific requirements of this Edition of Section XI would result in hardship and unusual difficulties without a compensating increase in the level of quality and safety. Therefore, relief is granted.
Relief Request R0012D, Pressure Retaining Welds in Vessels, Category B-B Item Bl.2 Weld AA:
Circumferential seam welds in bottom head is required to be volumetric (ultrasonic) examined. This examination includes the weld metal and base
- metal for one plate thickness beyond the edges of the weld.
Relief Request:
- l. Relief is requested to allow less than 100% of the code-required volumetric
( examination.
l Applicant's Basis for Request l The bottom head to reactor vessel circumferential weld AA is located at the edge i
of a bevel or transition in vessel diameter. The geometry is such that it
[ could be examined from only the vessel side of the weld.
i During preservice inspection, manual ultrasonic examination was performed from one side, (vessel shell side). This is required because of surface irregularity, (handgrinding causing pitch and roll profile) in the immediate weld area and the material transition area below the weld. The weld centerline location (measurement from tangent of transition) on the vessel shall may vary up to 2 l inches along the vessel circumference, (C = 730.42 in.). The pitch and roll profile along the slope transition plus the insufficient surface area measurement mitigates against providing a meaningful ultrasonic (45* and 60')
l examination.
The bottom head to reactor vessel weld AA was fabricated in accordance with ASME Section III Class 1 requirements. Weld has been volumetrically examined by radiography and hydrostatically tested and found acceptable in accordance with ASME Section III Class 1 requirements.
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l Preservice' inspections were performed where possible in accordance with ASME j Section XI 1974 Edition through and including Summer 1975 Addenda.
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Q All of the required adjacent base metal on the shell side of the weld and essentially 100% of the weld itself were examined by 45' and 60' angle beams normal to the weld. Approximately 50% of the adjacent base metal on the
' bottom head side of the weld was examined using 45* and 60' angle beams normal to the weld from the shell s'ide of the weld. The weld was examined 100% for transverse reflectors in both directions on the shell side of weld AA. There was essentially no coverage for transverse reflectors from the bottom head side of the weld and there was no coverage using 45' and 60' angle beams from the bottom head side of the weld.
Staff Evaluation and
Conclusion:
The staff has reviewed that applicant's request for relief, including the sketches showing the examination limitations. As a result of this review, the staff has concluded that a significant percentage of the code-required examination has been performed. To obtain information from the bottom head side of weld AA a transducer would need to be placed between weld AA and the vessel skirt. This is a relatively small area, the surface of which is irregular due to hand the slope transition. grinding and presents a pitch and roll profile along The distance between the weld AA and the top of skirt weld can also vary so that there would be insufficient space to place a transducer for a meaningful examination from the bottom head side of the weld AA.
The staff therefore concludes that the limited Section XI volumetric k
examinations and the Section III fabrication examination provide an acceptable level of preservice structural integrity and establish an adequate baseline
- examination record for future inservice inspection. Compliance with the
- specific requirements of this Edition of Section XI of the ASME Code would result in hardship and unusual difficulties without a compensating increase in the level of quality and safety. Therefore, relief is granted as requested. .
Relief Request R0012E, Pressure Retaining Welds, Head to Flange, Category B-C,
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Item 81.3
! Code Requirements:
i The head to flange weld is required to be volumetric (ultrasonic) examined l for preservice inspection in accordance with ASME Section XI,1974 Edition thorugh Summer 1975 addenda IWB-2500-1, examination category B-C, Item B1.3.
Relief Request:
1h Relief is requested to perform code required examination from one side only, j top head side only.
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4 Applicant's Basis for Request:
Weld was fabricated in accordance with ASME Section III Class 1 requirements.
Preservice inspections were performed in accordance with ASME Section XI 1974 Edition through and including Summer 1975 Addenda.
Due to the configuration, there is sufficient area to perform a meaningful ultrasonic examination from the top head side only (AH side of weld).
Weld has been volumetrically examined by radiography and hydrostatically tested, found acceptable in accordance with ASME Section III Class 1 requirements.
Weld was examined volumetrically (manual ultrasonic) from the AH side of the weld. There was no ultrasonic inspection coverage from the flange side of the weld. Full ultrasonic inspection coverage from the flange side of the weld.
Full ultrasonic inspection coverage was obtained for transverse and parallel reflectors from the AH side of the weld AG.
Staff Evaluation and
Conclusion:
The staff has reviewed the applicant's request for relief, including the
! attached sketches showing the examination limitations. As a result of this review the staff has concluded that a significant percentage of the Code t
required examination has been performed. Later editions of the Code supplement the volumetric examination with surface examinations. The staff also
! concludes that the position of the weld vis-a-vis the flange is such that ultrasonic inspection can not be performed on the weld. The staff further concludes that the limited Section XI volumetric examinations and the Section l III fabrication examinations provide an acceptable level of preservice structural integrity and establish an adequate baseline examination record for future inservice inspection. Compliance with the full requirements of XI would result in hardship and unusual difficulties by requiring a refabrication of the vessel head, without a compensating increase in the levef of quality and safety. Therefore, relief is granted.
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